The invention relates generally to tufting machines and methods of tufting and, more particularly, to tufting machines and tufting involving magnetically driven elements.
A tufting machine is comprised of a number of moving parts. For instance, a tufting machine has a needle bar which goes up and down moving needles into and out of a backing material that moves along a bedrail. The bedrail itself typically moves up and down to adjust the height of the pile. In addition to moving the needles up and down, the needle bar itself can move back and forth in order to create a pattern in the produced carpet. The tufting machine also has loopers that rock back and forth catching the loops of yarn as it passes through the backing material or a combination of hooks and knives that pivot about for grabbing and then cutting the yarn to create a cut pile carpet. The movement of all of these parts and elements must be synchronized in order to produce a carpet having a desired pattern of either loop pile or cut pile.
Conventionally, many of these parts of a tufting machine were mechanically coupled through a set of gears and belts. These types of tufting machines had a main timing shaft that was mechanically coupled to a set of secondary shafts for controlling the loopers, knives, hooks, and needles. This type of tufting machine, however, was troublesome in that it was difficult to change the type of carpet produced, such as by changing the pattern.
As an example of the difficulty in making an adjustment to a tufting machine, an explanation will now be given on how adjustments are made in a needle bar drive. A common needle bar drive includes a cam having a contour that dictates the shifting of the needle bar. In operation, the cam is rotated and the needle bar is coupled to the outer edge of the cam. A lobe or cut-a-way is produced along the surface of the cam in order to shift the needle bar in one direction and then the radius of the cam is increased in order to shift the needle bar back in the opposite direction. Thus, the needle bar is shifted according to a sequence determined by the contour of this cam.
A difficulty with using such a cam is that in order to change the pattern, a new cam having a different contour must be placed on the tufting machine. These cams are heavy and thus are not easily replaced. For instance, some cams weigh close to 75 pounds. Additionally, the tufting machine must be placed out of commission for a period of time, such as twenty to forty-five minutes, to replace the cams. If a new cam must be produced, machining the new cam may take an hour or more before it is even ready to be placed on the tufting machine. Furthermore, these cams eventually wear out and need to be replaced. In addition to the cams, the tufting machines also have sprockets. The sprockets control the number of times the needles go up and down relative to one rotation of the cam. To change the number of times, the sprocket would have to be replaced and the new sprocket would either speed that up or slow it down depending on its size.
Another approach to shifting the needle bar is to use a hydraulic drive. For example, U.S. Pat. No. 4,173,192 to Schmidt et al. which is incorporated herein by reference discloses a hydraulic actuator for transversely shifting the needle bar. Tuftco of Chattanooga, Tenn., manufacturers a hydraulic tufting machine called the HydroShift. This type of tufting machine requires a hydraulic actuator, an oil bin, filters, hydraulic lines, transducers, and a pump in order to hydraulically drive the needle bar. This type of tufting machine requires a great deal of maintenance and supervision due to the use of hydraulic fluids and lines. Furthermore, the pump produces a considerable amount of noise during operation, which can be quite bothersome.
Other examples of tufting machines are shown and described in U.S. Pat. No. 4,759,199 to Prichard, U.S. Pat. No. 5,005,498 to Taylor et al., U.S. Pat. No. 5,526,760 to Ok, U.S. Pat. No. 5,645,001 to Green et al., U.S. Pat. No. 5,794,551 to Morrison et al., and U.S. Pat. No. 5,979,344 to Christman, Jr., which are all hereby incorporated by reference. Some of these patents describe the use of servo motors and others describe screw actuators for use in driving the elements.
A common problem with many of these tufting machines is that they require a considerable amount of maintenance and supervision. For instance, the screw drives and other mechanically-coupled parts wear down over time, require maintenance, and are difficult to change over to a new setting. Another common problem for many of these tufting machines, especially with the needle shifting, is that the tufting machines require oil for lubrication for these moving elements and also for cooling. For instance, servo-driven tufting machines are oil cooled while many of the needle shifting bars have oil for lubrication. Unfortunately, this oil occasionally leaks from overhead, such as from a bin for lubricating the needle shifting mechanism, and comes in contact with the backing and the carpet being produced.
A need therefore exists for tufting machines that require less maintenance, result in less wear to the components, offer a quicker change over, and result in less spillage of oil than existing tufting machines.
The invention addresses the problems above by providing systems, tufting machines, and methods for tufting which require less maintenance, result in less wear in moving components, and also allow for a quicker change over when adjusting settings on the tufting machine. The moving components within these tufting machines do not require any bed or bath of oil to lubricate or cool the components. Furthermore, the movements can be precisely controlled to within a high degree of accuracy, at high speeds, and at controlled acceleration and deceleration. The movements may furthermore be programmed for allowing an easy and quick changeover to new settings.
In the preferred embodiments, the tufting machines use linear servo motors, and more preferably, magnetic drives. For instance, a shifting needle bar may be comprised of at least one rod attached to the linear motor for controlling the shifting of the needle bars. A position sensor associated with the linear drive provides position information to a processor which also generates control signals for precisely controlling the shifting of the needle bar. With such a linear drive, the needle bar can be shifted at speeds more than 800 to 1000 times a minute. This type of drive eliminates the need for any conversion between rotary to linear motion and also does not require hydraulic drives. The tufting machine with this type of shifting mechanism for the needle bar can therefore eliminate an oil bin placed above the tufting machine intended to lubricate the shifting needle bar. Consequently, the tufting machines according to the invention result in less spillage of oil onto the carpet and backing material. The tufting machines also offer a more quiet operation, which is a substantial improvement over many tufting machines, especially the hydraulically driven tufting machines.
In addition to the needle shifting mechanism, tufting machines according to the invention preferably include linear drives for moving the needles up and down, for lowering or raising the bed rail, for pivoting the hooks and knifes, and for rocking the loopers. A preferred tufting machine according to the invention need not have any main drive shaft as well as no associated cams, belts, and gears that are tied to the main shaft. The tufting machines according to the invention can be highly programmable with the processor controlling the various linear drives to synchronize the movements of the components. For instance, an encoder can be used to generate the timing signals for the various linear drives, with this encoder being associated with a main shaft or with the backing feed, such as on a roller.
The tufting machines according to the invention encompasses both entirely new tufting machines constructed with the drives according to the invention as well as tufting machines retrofitted to have one or more of the linear drives.
Other advantages and features of the invention will be apparent from the description below.